This invention relates to a bushing for connecting high strength tool handles made of fiberglass to conventional tool heads as replacements for conventional wooden handles.
Eyes found in conventional tool heads often have a double taper or venturi shape that is intended to receive the tongue of a wooden handle having a decreasing single taper. The tongue's tapered surface engages the decreasing taper in the venturi-shaped eye. The end of the tongue is then spread open to engage the increasing taper of the eye by a wedge driven into the end of the tongue.
The tongues of fiberglass handles cannot be satisfactorily spread with a wedge and thus cannot be attached to conventional tool heads in the conventional manner.
Bushings for connecting fiberglass handles to tool heads having conventional double tapered or venturi-shaped eyes have been developed and are described in my U.S. Pat. No. 3,819,288. Such bushings, longitudinally split into two sections, make it possible to fit high strength fiberglass or any reinforced handle shaft that is essentially non malleable handles into tool heads having conventionally shaped eyes. The bushings or adapters are placed between the handle and tool head and are held in place on the handle by transverse key-like projections on the interior of the the bushing which engage transverse slots in the handle.
In order to accommodate variations in both the size of the eye in tool heads and the size of handles, spacers and shims can be placed between the handle and the bushing sections. These spacers and shims move the bushing sections outwardly from the handle and increase the outside dimension of the bushing.
In the previous construction, as the bushing sections are moved outwardly from the handle by the insertion of spacers, the area of engagement between the projections and the handle slots is reduced. Should the area of contact of between the projections and slots be greatly reduced, significant stresses could be induced at or near that area when the tool is used. Failure at such stress point could in the prior construction result in the bushing sliding off the tongue of the handle. Thus, to reduce the possibility of such stresses there existed a need for an improved bushing which will prevent longitudinal axisl movement of the bushing with respect to the handle even when the area of contact between the projections and slots is reduced. Such an improved bushing would ideally be easy to install, be configured so as to match the conventional venturi shape of the eye in the tool head. The improved bushing with the associated spacers is further capable of being adapted to fit a wide range of sizes of eye holes.
The present invention fulfills those needs.